Compositional Variation of Metallorganic Chemically Vapor Deposited SrTiO[sub 3] Thin Films along the Capacitor Hole Having a Diameter of 0.15 μm

Hwang, Cheol Seong; Park, Jaehoo; Hwang, Doo Sup; Yoo, Cha Young

doi:10.1149/1.1409399

Cited by 10 publications

(24 citation statements)

References 12 publications

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“…For PZT film, the thickness at the bottom of the trench was larger than that at the top. Same deposition characteristic was also reported for the MOCVD-SrTiO 3 films deposited on Ru layers by Hwang et al [14]. They pointed out the possibility of the compositional variation by the decrease of the diffusion speed of the precursor molecules in the small sized holes.…”

Section: Methodssupporting

confidence: 75%

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Funakubo

Nagai

Minamidate

et al. 2006

Integrated Ferroelectrics

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Three dimensional capacitors of Pb(Zr,Ti)O 3 [PZT] together with the Ru electrodes were tried to deposit by metal organic chemical vapor deposition for realizing high density ferroelectric random access memory (FeRAM). Good conformability was obtained for both of CVD-Ru and PZT layers on the trenched substrates by optimizing the deposition conditions. In addition, PZT films deposited on Ru bottom electrode showed the good compositional conformability. Finally we demonstrated the Ru/PZT/Ru three dimensional capacitor. These data accelerate the development of three dimensional PZT capacitors.

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Section: Methodssupporting

confidence: 75%

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Funakubo

Nagai

Minamidate

et al. 2006

Integrated Ferroelectrics

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“…This distribution of cation composition is better than the large distribution of more than 30% reported for films deposited by MOCVD. 1,3,4 Although the process was not an ideally self-regulated one, the very slow gradient of the Pb/ Ti ratio against V͑Pb͒ shown in Fig. 6 could be the reason for better cation composition uniformity compared to MOCVD.…”

Section: B Incubation Periodmentioning

confidence: 99%

“…Recent studies have indicated a serious problem in that multicomponent oxide films deposited over 3D structures by MOCVD exhibit nonuniformity in cation composition, although film thickness appears to be uniform over the complex structure. [1][2][3][4] In MOCVD, surface reaction limiting deposition, where the deposition rate depends only on the substrate temperature, has been a common approach to achieving a homogeneous 3D coverage. However, at a mutual deposition temperature, not every precursor necessarily decomposes under the surface-reaction limiting condition.…”

Section: Introductionmentioning

confidence: 99%

Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Watanabe

Hoffmann‐Eifert

et al. 2007

Journal of Applied Physics

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Ternary PbTiOx films were deposited at 240°C on Pt-covered Si substrates using a combination of liquid injection atomic layer depositions of binary TiOx and PbO films. Ti(OC3H7)2(C11H19O2)2 [Ti(Oi−Pr)2(DPM)2] and Pb(C11H19O2)2 [Pb(DPM)2] dissolved in ethylcyclohexane and H2O were used as source materials. The deposition rates of Pb and Ti were enhanced in the ternary process compared to their binary processes under comparable deposition conditions. The Pb∕Ti ratio of PbTiOx films saturated with an increase in Ti precursor input, while it continued to increase with an increasing Pb precursor input. The self-regulated growth nature of the Pb–O layer in the binary film growth was lost in the mixed PbTiOx process as a result of interaction with the predeposited Ti–O layer. It was confirmed that for the PbTiOx film to grow on Pt substrates, an initial incubation period is required. Both Pb–O and Ti–O layers shared a common incubation period of up to ten sequences. The incubation period was shortened by increasing the input of Pb precursor. It was independent of the input of the Ti precursor and the order of precursor supply. This variable incubation period was considered as a potential key issue for growing stoichiometric and uniform multicomponent films over three-dimensional (3D) structures. The order of precursor supply affected the effective deposition rate after the incubation period. A sequence starting with a Ti precursor injection showed a higher growth rate than a sequence that started with a Pb precursor supply. A PbTiOx film was deposited on a 3D substrate precoated with an Ir layer to demonstrate the uniformity in film thickness and cation composition. Although the present PbTiOx process does not have an ideal wide-process window in the cation composition, the PbTiOx film showed uniform coverage and the distribution of cation composition over the hole structure was within ±10%.

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“…13 The results are summarized in Table I for comparison. It can be clearly understood that the film grown on the bottom region of the hole has a Ti-excess composition.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the deposition behavior in the two chambers were expected to be similar. The deposition conditions and results from shower I have been reported earlier 13 and are again presented here as a comparison. For shower I, the wafer, shower head, and wall temperatures during deposition were 420, 235, and 170°C, respectively.…”

Section: Methodsmentioning

confidence: 90%

Cation Composition Control of MOCVD (Ba,Sr)TiO[sub 3] Thin Films along the Capacitor Hole

Hwang

Park

et al. 2002

J. Electrochem. Soc.

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The variations in the cation concentration ratio of metallorganic chemically vapor deposited ͑MOCVD͒ (Ba,Sr)TiO 3 ͑BSTO͒ and SrTiO 3 ͑STO͒ thin films along a capacitor hole with a diameter of 0.15 m were investigated. Even under deposition conditions that would produce cation-stoichiometric films on a nonpatterned wafer, the (Ba ϩ Sr)/Ti and Sr/Ti ratios varied remarkably along the depth direction of the hole when the usual shower-head-type chemical vapor deposition chambers were used. The Sr/Ti ratios increased or decreased depending on the wafer temperature, the flow rate, and the types of precursors. When a new dome-type chamber was adopted and the dome temperature was 450°C, completely conformal composition and thickness step coverages were obtained at a wafer temperature of 420°C on the 0.15 m capacitor hole pattern. The variation in the composition and thickness step coverages were interpreted in terms of the variation in the sticking coefficients of the precursors according to the various deposition conditions and types of precursors and chambers.The low-temperature (Ͻ500°C) metallorganic chemical vapor deposition ͑MOCVD͒ process used for producing (Ba,Sr)TiO 3 ͑BST͒ thin films is becoming crucial for merged memory and logic ͑MML͒ and dynamic random access memory devices ͑DRAM͒, which require minimum feature sizes of Ͻ0.10 m. 1-3 Good film step coverage over a severe 3D surface topology and nondamaging deposition on the underlying electrode stack are the key merits of the low-temperature process over the high-temperature (Ͼ600°C) process. The expected capacitor structure for sub-0.13 m devices is a contact hole type. 1-3 This is mainly because of the difficulty in etching a noble metal electrode, such as Pt and Ru, to the node-type bottom electrode with lateral dimensions of Ͻ0.13 ϫ 0.33 m and a height Ͼ0.5 m.However, conformal deposition over the entire surface area of such an extreme geometry in terms of the chemical composition as well as the thickness has not necessarily been confirmed, even for the low-temperature MOCVD. Furthermore, obtaining conformal deposition on a hole-type structure is much more difficult when compared to that on a node-type structure with the same aspect ratio.There have been many reports regarding MOCVD of the BST thin-film deposition process, 4-6 hardware, 7 precursor chemistry, 8,9 and electrical performance. 10,11 However, to the best of the authors' knowledge, there is a paucity of reports on the nonuniformity of the cationic composition in BST thin films deposited on hole patterns. Yamamuka et al. 12 investigated the thickness and composition variations of SrTiO 3 ͑STO͒ thin films by MOCVD at 420°C using a computer simulation and deposition experiment on a trench pattern. However, they were unable to observe a composition variation. The authors have reported a composition and thickness variation of a MOCVD STO film deposited at a wafer temperature of 420°C on a capacitor hole pattern with dimensions of 0.15 ϫ 0.40 ϫ 0.57 m when the usual shower-head-type MOCVD chamber was...

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Compositional Variation of Metallorganic Chemically Vapor Deposited SrTiO[sub 3] Thin Films along the Capacitor Hole Having a Diameter of 0.15 μm

Cited by 10 publications

References 12 publications

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Trial for Making Three Dimensional PZT Capacitor for High Density Ferroelectric Random Access Memory

Growth of ternary PbTiOx films in a combination of binary oxide atomic layer depositions

Cation Composition Control of MOCVD (Ba,Sr)TiO[sub 3] Thin Films along the Capacitor Hole

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